The function of thermal barrier coating is to protect the hot components of advanced aero-engines from hot corrosion and ensures the hot components service in high-temperature environment safely. In general, a low thermal conductivity and a high fracture toughness are the key performance indexes for the selection of novel thermal barrier coating materials. In this work, a high-entropy rare-earth tantalate ceramic of (Y0.2Dy0.2Sm0.2Yb0.2Er0.2)TaO4 (i.e. (5RE0.2)TaO4) with the superior properties was synthesized via solid-state reaction. The results indicate that (5RE0.2)TaO4 exhibits a low thermal conductivity (i.e., 1.68 W·m-1·K-1 @ 900 ℃) and a high thermal expansion coefficient (i.e., 10.0×10-6 K-1 @ 1 200 ℃). (5RE0.2)TaO4 shows a high fracture toughness (i.e., 2.6 MPa·m1/2) and a low brittleness index (i.e., 2.1 μm-1/2) because of the unique ferroelastic toughening effect. In addition, (5RE0.2)TaO4 also has a promising application prospect as one of thermal barrier coating materials.